Method of testing an automobile battery and electrical system while in circuit, using a booster battery

ABSTRACT

A combination booster and automobile electrical system tester, including a booster battery, polarity protector, voltmeter, remote control switch, operational indicator lights and interconnecting cables all mounted on a handtruck-type cart with a detachable handle, for making comparison tests of the voltages present in an automobile electrical system with and without the starter cranking and with and without the booster battery connected.

United States Patent Channing 1 Jan. 25, 1972 4] METHOD OF TESTING ANReferences Cited ELECTRICAL SYSTEM WHILE IN I 993 444 3/1935 H k, 324 295 CIRCUIT, USING A BOOSTER 212291009 1,194,823;???3:::1J1331:1j::1iiiijiijjjiiiiisaiz is BATTERY 2,780,777 2 1957Sammis et al ..324/29.5 [72] Inventor: Harry M. Channing, Reading, Pa.3,356,935 12/1967 Morgan ..324/l6 [73] Assignee: General Battery andCeramic Corp., Read- Primary Examiner-Rudolph V. Rolinec ing, Pa.Assistant Examiner-R. .l. Corcoran Filed: p 1969 Attorney-Schapp andHatch [2]] Appl. N0.: 819,650 [57] ABSTRACT Rdated Application Data Acombination booster and automobile electrical system tester, Including abooster battery, polarity protector, voltmecommuailon'm-pan 0f 578,727,p 12, ter, remote control switch, operational indicator lights and in-1966, abandonedterconnecting cables all mounted on a handtruck-type cartwith a detachable handle, for making comparison tests of the [52] US. Cl..324/29.5, 733/118, 324/73 lt esent in an automobile electrical systemwith and 27/42 without the starter cranking and with and without thebooster [58] Field of Search ..324/29.5, 16, 73, 15; 340/249; batteryConnecte 5 Claims, 2 Drawing Figures EXTEIZNAL aArrz/zv l w MENU:

/6 EXTEKNAL flffrl/[AL SYSTEM PAT-ENTED JAuzslsnz (EXTERNAL BATTERYSYSTfM FIE--2- /6 EXTERNAL ELfCTK/[AL INVENTOR. HARRY M. CHANN/NG METHODOF TESTING AN AUTOMOBILE BATTERY AND ELECTRICAL SYSTEM WHILE IN CIRCUIT,USING A BOOSTER BA'I'IERY CROSS-REFERENCES TO RELATED APPLICATIONS Thisapplication is a continuation-in-part of my copending application Ser.No. 578,727, filed Sept. l2, 1966, and entitled TESTING AND BOOSTERPOWER SUPPLY UNIT now abandoned.

BACKGROUND OF THE INVENTION The present invention relates toimprovements in a method of comparison testing, and more particularly toa test method selectively substituting a booster battery in anautomobile electrical system while protecting against damaging suchsystem because of incorrect hookup.

With the increased use of batteries with one-piece covers, where it isno longer possible to test individual cells, it has been necessary todevelop new battery-testing equipment. The need for new equipment inthis field has been given further impetus by the addition to modern carsof more power-consuming accessories, and by the trend toward use ofaltemators rather than conventional direct current generators forsupplying the electrical power. Furthermore, the ever-increasing numbersof automobiles on the road has accelerated the demand for rapid and yetaccurate trouble-shooting and servicing of the problems of theelectrical systems of those automobiles by people of less skill than ajourneyman mechanic, such as by service station attendants or emergencyroad service technicians.

Some of the simplest and yet most valuable tests of an automobileelectrical system may be obtained with the apparatus of the presentinvention, which enables the operator to measure the voltage in theautomobile electrical system using the automobiles own battery, bothwith the starter cranking and without, and which also enables theoperator to make the same two tests with a freshly charged high-capacitybooster battery connected to the electrical system of the automobile.Problems have arisen, however, with equipment permitting directconnection of the booster battery to the automobile electrical system inthe case of automobiles which have alternator-type electrical systems,as alternator-type systems may be severely damaged if the boosterbattery is hooked up with polarity reverse to that of the automobileelectrical system. Improper polarity of connection may also damage otherelectrical accessories of the automobile such as transistorized ignitionsystems, radios, and tape players.

SUMMARY OF THE INVENTION To prevent such damage, it is essential toequip booster battery sets with a polarity'sensing device which preventselectrical connection of the booster battery to the automobileelectrical system unless the polarity of the electrical system is thesame as that of the booster battery, that is to say, unless the operatorhas attached the connecting cables of the testing apparatus in properpolarity relationship to the poles of the automobile electrical system.A further advantage of such a polarity protector which preventscompletion of the circuit between the booster battery and the cableswhich attach the test apparatus to the automobile electrical systemuntil such time as the polarity protector senses the appropriatepolarity is that the clips on those cables are thereby kept deenergizeduntil they are properly attached so that the booster battery is notshorted out by accidental contact of the clips with each other or with acommon conductor. This yields the dual benefit of preventing dissipationof the charge of the booster battery through such accidents and thesafety of preventing potentially hazardous sparking through suchshort-circuiting. Sparks are a particular danger around freshly andrapidly charged batteries, as hydrogen gas may be evolved in the rapidcharging process, which could explode upon ignition by an accidentalspark.

As the present apparatus is designed for in the field" use as well asuse in regular full-service repair establishments, a highly desirablecompact and readily portable unit is provided. The equipment ideally iscombined into one integral unit which can easily be rolled around fromautomobile to automobile and which facilitates loading of the apparatusinto a wide variety of vehicles which might be used to render emergencyroad service to stalled cars. Accordingly, all of the electricalcomponents of the present apparatus are mounted on a cart of thehandtruck type, with-a handle on the cart so that it may be convenientlywheeled along by a man walking with it. To increase the compactness andease of handling of the apparatus, in the preferred embodiment ofapplicant's invention, a portion of the handle is made demountable fromthe lower portion of the cart so that the apparatus may be inserted intoor through a space with limited vertical clearance. Making an integralunit of the apparatus by mounting all of its cooperative components onthe cart assures that no part of the apparatus will become separatedfrom the rest and left behind, and provides further assurance that acareless user of the apparatus will not misconnect the booster batteryto the polarity protector or use the booster battery with ordinaryjumper cables lacking polarity protection.

The testing apparatus of the present invention is intended both fordiagnostic use by service personnel working on the automobile and fordirect demonstration of the condition of the electrical system of theautomobile to the owner by service personnel. For such demonstrationusage, it is advantageous to have simple and straight-forward appearingapparatus which the owner can observe while the testing takes place.This is facilitated by the unitary nature of applicants testingapparatus.

It is therefore a principal object of the present invention to provide aunitary testing and booster power supply apparatus adapted both to startstalled automobiles and to test automobile electrical systems.

It is a further principal object of the present invention to providetesting apparatus of the character described in which the automobileelectrical system is protected against imposition of direct current ofpolarity reverse to the proper system polarity.

Another object of the present invention is to provide electrical testingapparatus of the character described adapted for attachment to theelectrical system of an automobile to measure the voltage present inthat system under selected load conditions and with selected sources ofpower supply.

A further object of the present invention is to provide a testing andbooster power supply unit of the character described in which graphicindication is given of correct or incorrect hookup to the automobileelectrical system and of whether or not the booster battery isoperatively connected into the automobile electrical system.

A still further object of the present invention is to provide anelectrical testing and booster supply unit in which the booster powersupply is connected into the automobile electrical system by remotecontrol means allowing the user of the testing apparatus maximum freemovement and eliminating the potential hazard of sparking nearbatteries.

Yet another object of the present invention is to provide an electricaltesting unit of the character described in which the cables forconnecting the unit to the electrical system are kept out of connectionwith the booster power source until after connection to the automobileelectrical system to prevent discharge and damage to the booster powersource and to prevent potentially hazardous sparking in the vicinity ofthe automobiles battery.

Further objects and advantages of the invention will appear as thespecification proceeds, and the new and useful features of the testingand booster power supply unit will be fully defined in the claims heretoattached.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERREDEMBODIMENTS Referring to the drawings in detail, it will be seen thatthe testing and booster power supply unit 11 of the present inventionessentially comprises a polarity protector 13 adapted for connection toa source of direct current 14 and to the electri-v cal system 16 of anautomobile 12,.together with a test meter 17 connected to polarityprotector 13 for measuring the voltage present in electrical system 16.Polarity protector 13 is formed to control operative electricalconnection of the source of direct current 14 to the automobileelectrical system 16 in response to the polarity of the latter.

In the preferred form of applicants invention, as shown in thesedrawings, the source of direct current 14 is a conventional l2-voltautomobile storage battery 18 of high amperehour capacity, and boosterbattery 18, the polarity protector 13, and the test meter 17 are mountedon a handtruck-type wheeled cart 19 to provide a unitary, compact andreadily transportable testing and booster power supply unit.

Polarity protector 13 is equipped with connecting cables 20 and 21having conventional clips 22 attached thereto for connecting cables 20and 21, and thereby polarity protector 13, to electrical system 16 ofautomobile 12. A remote control means 23 is connected to polarityprotector l3 and consists of remote control switch 26 coupled topolarity protector 13 by a cable 24. As may be seen from FIG. 2, remotecontrol means 23 is in a series operational relationship with polarityprotector 13 so that concurrent closure of remote control switch 26 andsensing of correct polarity of electrical system 16 by polarityprotector 13 is required before booster battery 18 will be connectedinto electrical system 16. Cables and 27 are also provided to connectbooster battery 18 to the circuitry of polarity protector 13.

Test meter 17 may be a conventional volt meter of appropriate voltagerange with a scale calibrated to indicate satisfactory andunsatisfactory ranges of voltage present in system 16 under the varyingload and power supply conditions under which the tests are made. As hereshown, test meter 17 is built into a housing 28 attached to cart 19, butit should be appreciated that the test meter 17 could be enclosed in aseparate housing readily removable from cart 19 and supplied withappropriate clip leads (not shown) to allow removable connection of testmeter 17 to the circuit of polarity protector 13.

Mounted in housing 28 and connected into the circuit 29 of polarityprotector 13 are indicators 31, 32 and 33 for indicating correct andincorrect connection of testing apparatus 11 to electrical system 16 andfor indicating operative connection of booster battery 18 to system 16.In the preferred form of the invention shown here, indicators 31, 32 and33 are small indicator lamps of appropriate voltage rating, withindicator 31 being colored red, indicator 32 being colored green, andindicator 33 being colored yellow for the greatest ease of visualdistinction between them. Red indicator 31 denotes improper connectionto system 16, green indicator 32 denotes proper connection to system 16,and yellow indicator 33 indicates the operative electrical connection ofbooster battery 18 into automobile electrical system 16.

Cart '19 isfbimed with a platform 34 having a handle portion 36projecting upwardly therefrom for maneuvering the cart and forsupporting housing 28 which contains polarity protector 13 and meter 17.Attached to platform 34 and handle portion 36 is an axle 37 on which aremounted for rotation wheels 38 for assisting in the movement of theapparatus. As here shown, cart 19 is formed with handle portion 36having a portion 39 thereof extending generally horizontally beneathplatform 34 to support the platform and then being bent downwardly toform a leg 41 to provide a third point of support for the apparatus.Cart 19 is also provided with a railing 42 surrounding platform 34 toassist in retaining booster battery 18 thereon. Brace members 43 extendfrom railing 42 to handle portion 36 to reinforce railing 42 andplatform 34. Handle 36 is provided with hooks 44 for convenient storageof cables 20, 21 and 24.

The upper portion of handle 36 is detachable from the lower portion ofthe handle by means of a telescoped joint 46 preferably located abovethe point of attachment of brace members 43 to handle 36 and below thepoint of attachment of housing 28. Joint 46 may be secured againstaccidental disengagement by a screw 47, or by other appropriate meanssuch as a spring-loaded ball latch. Making the upper portion of handle36 demountable at joint 46 allows the user to remove the upper portionof the apparatus, including housing 28, to render the apparatus morecompact for transportation in a space of limited clearance. Theapparatus may then be easily and quickly reassembled and used or wheeledaround in its assembled form at any convenient location, as desired.

In the electrical circuit of the testing apparatus, as shown in FIG. 2,a transistor 48 acts as a switching device to operate a heavy-duty relay49 which in turn, upon its closure, connects booster battery 18 into theautomobile electrical system 16. Transistor 48 may be of any type havingthe appropriate power-handling characteristics but should be ofsufficient rating to pass the amount of current required to energizerelay 49. In the preferred form of the present invention, transistortype 2N555, manufactured by Motorola, is used. This transistor is aPNP-transistor but an NPN-transistor 'could be used with thewell-understood reversal of the polarity of its connections.

The positive pole of booster battery 18 is connected to a heavy gaugepower cable 25 which for reasons of convenience passes into and throughhousing 28, exiting from housing 28 as positive connecting cable 20 andcontinuing therefrom to one of connector clips 22 attached to a positivepole in the electrical system 16 of automobile 12. The negative pole ofbooster battery 18 is connected to a cable 27 leading into housing 28and connecting therein to one contact of relay 49. The other contact ofrelay 49 is connected to a heavy gauge connecting cable 21 which exitsfrom housing 28 and leads to the other of connecting clips 22 which isconnected to a point of negative polarity in the electrical system 16 ofautomobile 12. Contained within the outer covering of cable 25 butinsulated from contact therewith is a lead 51 which enters housing 28with cable 25 but then separates from that cable.

The emitter of transistor 48 is connected in series with remote controlswitch 26 in a lead 52 which connects with lead 51. The collector oftransistor 48 is connected through lead 53 to one terminal of theenergizing coil of relay 49. Indicator 33 is connected between lead 53and cable 27. The base of transistor 48 is connected through baseresistor 54 to a lead 56 which is common to one terminal of indicators31 and 32 and is also connector to the other terminal of the energizingcoil of relay 49 and to cable 21. In the preferred form of thisinvention, base resistor 54 is of the value of ohms, but it should beappreciated that if other transistors are chosen than the one here used,the appropriate value of base resistor 54 should be selected inaccordance with the characteristics of the transistor used.

As mentioned above, one terminal each of indicators 31 and 32 isconnected to lead 56 which leads in turn to cable 21. The other lead ofindicator 31 is connected to the anode of a diode 57, and the cathode ofdiode 57 is connected to lead 52. The

other terminal of indicator 32 is connected to the cathode of a diode58, and the anode of that diode is connected to lead 52.

Leads 59 and 61 are contained within-cables 20 and 21, respectively, ina fashion similar to the inclusion of lead 51 in cable 25. Lead 61 isconnected directly to one terminal of test meter 17. Lead 59 isconnected to one of the switch contacts of a relay 62. The other switchcontact of relay 62 is connected to the other terminal of test meter 17.Connected across the switch contacts of relay 62 is a series resistance63 for test meter 17. The switch contacts of relay 62 are of thenormally closed variety so that upon energization of the coil of relay62 with the appropriate current, the switch contacts will be opened toplace series resistance 63 into the test meter circuit, while in theabsence of sufficient energization of relay 62, series resistance 63 isshorted out by the closed switch contacts of relay 62.

One terminal of the energizing coil of relay 62 is connected to lead 56,and the other terminal of the energizing-coil of relay 62 is connectedthrough a lead 64 to lead 51. Test meter 17, series resistance 63 andrelay 62 are available as a single packaged commercial unit from theChristie Electric Corporation of Los Angeles, Calif., in a unitdesignated as the Christie T-2 Tester. The test meter has a range ofapproximately 7.5 volts DC full scale, and series resistance 63 ispreferred to be of the order of 2,940 ohms. It should be appreciated,however, that if other meters than the one contained in the Christie T-2unit are used as test meter 17, the value of series resistance 63 shouldbe appropriately selected to match the characteristics of the meter usedfor the purpose of converting the meter to approximately double thescale reading, or volts DC full scale. Relay 62 is selected to have apull in potential somewhat less than 12 volts DC and considerablygreater than 6 volts DC, such as 9 or 10 volts DC As here shown, relay62 may be a type 2X1A3C1, l2-volt DC coil, as manufactured by GlobeElectric Manufacturing Company, Gardena, Calif.

In operation, relay 62 and series resistance 63 operate to automaticallyconvert test meter 17 for use with 6 or 12 volt electrical systems inautomobile 12. Upon connection of cables and 21 to electrical system 16,if the system is 6 volt, the 6-volt potential will not be enough toenergize the coil of relay 62, along the circuit consisting of cable 20leading from the positive pole of electrical system 16 to the positivepole of booster battery 18 and thence along lead 51 and 64 to the coilof relay 62 and from the negative pole of electrical system 16 alongcable 21 to lead 56 and thence to the other terminal of the energizingcoil of relay 62. Thus, the contacts of relay 62 will remain closed,shorting series resistance 63 out of the meter circuit, and resulting in6-volt operating characteristics of test meter 17. Should electricalsystem 16 be of the 12 volt variety, the potential applied along theabove circuit to the energizing coil of relay 62 will be sufficient tocause its actuation, opening its switch contacts, and placing seriesresistance 63 into the meter circuit, converting the test meter 17 for12 volt operation.

In the overall operation of the testing apparatus for diagnosticpurposes, the apparatus is wheeled up on cart 19 to a position such thatthe electrical system 16 of automobile 12 is accessible to cables 20 and21 and yet meter 17 and indicators 31, 32 and 33 are readily visible tothe service operator and to the customer. The service operator attachesclips 22 to the electrical system 16 of automobile 12 at a convenientpoint which may be the terminals of the customers battery 66.

Should the service operator by mistake apply cable 21 to the positivepole of the customers battery and cable 20 to the negative pole, twoeffects may be noted. The first of these is that a positive potentialwill be applied to the anode of diode 57 through cable 21 and lead 56and a negative potential will be applied to the cathode of diode 57through cables 20 and 25 and lead 51. Diode 57 will then conductcurrent, lighting indicator lamp 31 indicating improper polarity ofconnection of clips 22 to electrical system 16. I

The second effect to be noted is that should the service operator closeremote control switch 26 despite the improper connection to electricalsystem 16, a positive potential will be applied through base resistor 54to the base of transistor 48,

biasing transistor 48 toward cutoff. As transistor 48 is cutoff,electrons do not flow from the lead 52 through the emitter to thecollector and thence to lead 53 to energize the coil of relay 49. It istherefore not possible, even after closure of remote control switch 26,to cause booster battery 18 to be connected to automobile electricalsystem 16 if clips 22 have been applied to the wrong poles of system 16.Red indicator lamp 31 thus serves to warn the service operator of hiserror and of the reason why the testing apparatus remains inoperative,and also warns him to correct the polarity of connection of clips 22 toelectrical system 16 in order to prevent damage to test meter 17 throughprolonged connection to a source of the wrong polarity of current.

With cables 20 and 21 incorrectly connected, green indicator lamp 32will not be lit, as current flow between line 56 and line 52 is blockedby diode 58 through the application of positive potential to the cathodeof that diode and application of negative potential to the anode of thatdiode. Yellow indicator lamp 33 will likewise not be energized, as thecircuit between lines 52 and 53 is interrupted by transistor 48 which isbiased to cut off.

if clips 22 are applied correctly to electrical system 16 to connectcable 20 to the positive pole of the electrical system 16 and cable 21to the negative pole, two effects may be noted. The first effect is thatthrough application of negative potential to the cathode of diode 58 andto the anode of diode 57 along lead 56, together with application ofpositive potential to the anode of diode 58 and to the cathode of diode57 along lines 52, S 1, cable 25, and cable 20, diode 58 will conductcurrent and diode 57 will block the flow of current so that indicatorlamp 31 will not be lit, but indicator lamp 32 will be lit to indicatethe correct polarity of connection of clips 22 to automobile electricalsystem 16.

The second effect to be noted is that a negative potential will beapplied along lead 56 to the base of transistor 48 through base resistor54. Upon closure of remote control switch 26, a negative bias will besupplied to the base of transistor 48, biasing it toward saturation.Transistor 48 will then pass current between line 52 and line 53 toenergize the coil of relay 49, thereby closing the switch contacts ofrelay 49 to connect booster battery 18 to the electrical system 16 ofautomobile 12. The passage of current between lines 52 and 53 due toconduction by transistor 48 also lights yellow indicator lamp 33 toindicate that the booster battery 18 has been operatively connected intoautomobile electrical system 16.

The diagnostic procedure for the testing apparatus may be conducted asfollows: the service operator, after making the correct connection ofclips 22 to electrical system 16, can read for his own diagnostic useand can demonstrate to the customer the voltage indicated on test meter17, which will be an indication of the state of charge of the customersbattery 66. if the automobile 12 has been operated recently, it may benecessary to disconnect the coil wire of automobile 12 to prevent theengine from starting and to operate the starter of automobile 12 for afew seconds to dissipate any surface charge on battery 66 which mightdistort the readings by test meter 17.

After the service operator has measured the voltage level of thecustomers battery 66 under no load conditions, the starter of automobile12 may be operated to place the customers battery 66 under heavy loadconditions. Test meter 17 will again indicate the voltage in electricalsystem 16 to inform the service operator and demonstrate to the customerthe ability of the customers battery 66 to perform under loadconditions. This test gives an indication of the overall condition ofthe customers battery 66, and of its ability to be recharged.

If both of the above tests result in satisfactory voltage readings ontest meter 17, the customer may be assured that his battery 66 is ingood condition. Should the customers battery 66 perform unsatisfactorilyaccording to the readings of test meter 17 under load conditions, theservice operator may substitute the booster battery 18 into the circuitin parallel with the customers battery 66 by closure of remote controlswitch 26 to compare the performance of electrical system 16 whensupplied with power by booster battery 18 with the performance whensupplied by the customers battery 66. Yellow indicator 33 serves as aguide to the interpretation of the readings of test meter 17 byindicating whether the electrical system 16 is being evaluated with thebooster battery 18 connected to it, or without the booster battery.

Should test meter 17 indicate satisfactory voltage readings under loadwith the booster battery 18 connected into the electrical system 16, theproblems of electrical system 16 are thereby vividly demonstrated to liewith the customers batte ry 66. Should the readings of test meter 17under heavy load, i.e., with the starter cranking, remain unsatisfactoryafter booster battery 18 is connected into electrical system 16, one ofthe connecting cables to the customers battery 66 may be removed fromthe customers battery and the corresponding clip 22 connected directlyto the connecting cable to isolate the customers battery 66 fromelectrical system 16. If the readings of test meter 17, under load, withthe starter cranking, remain unsatisfactory after the customers battery66 is thereby removed from the system, the problems of electrical system16 are demonstrated to lie either with the starter or connecting cablesof electrical system 16 of automobile 12.

During all of the foregoing tests under load with the starter ofautomobile l2 cranking, the coil wire of automobile 12 has beendisconnected to prevent the operation of the starter from starting theengine. To continue the diagnostic evaluation of electrical system 16,the coil wire may be reconnected and the starter of automobile l2permitted to start the engine. With the engine of automobile 12 runningand clips 22 still connected to electrical system 16, test meter 17should indicate the voltage output of the generator or alternator systemof the automobile. For example, too low voltage might indicate a defectin the generator, while too high a voltage might indicate improperoperation of the voltage regulator.

Should the customers battery 66 be so dead as to be unable to produceany negative potential upon application of clip 22 to its negative poleso as to bias transistor 48 toward saturation, the service operator mayoverride this polarity protective feature of the testing apparatus bytouching the clip 22 which is attached to cable 21 to the negative poleof the booster battery 18 while holding remote control switch 26 closed.This will apply the necessary negative bias to transistor 48 to cause itto conduct, thereby energizing relay 49 to close its switch contact andsupply the negativebias from the negative pole of the booster batteryalong line 56 to the base of transistor 48 to keep transistor 48 in thesaturation mode. The service operator then holds remote control switch26 closed continuously while he removes clip 22 bearing cable 21 fromthe negative terminal of booster battery 18 and, after carefullyascertaining the negative pole of electrical system 16, applies cable 21to that pole.

Great care must be exercised to select the correct pole of automobileelectrical system 16, as the polarity protection apparatus of thetesting apparatus has been bypassed and severe damage may be done toelectrical system 16 if the improper polarity is imposed upon it by thistechnique. However, the use of this technique enables the serviceoperator to use the booster battery to start automobile 12 if it isstalled by a completely dead battery 66 and to evaluate the starter,cables,

generator, voltage regulator or alternator of automobile 12, as

outlined above. If the clip 22 bearing cable 21 is applied to thenegative terminal of booster battery 18 without closure of remotecontrol switch 26, test meter 17 may thereby be used to measure thestate of charge of booster battery 18 to ensure that it is fullycharged.

The testing apparatus may also be used to perform the normal function ofa booster battery in starting the engines of automobiles whose ownbatteries are dead. This use may or may not be accompanied by the use ofthe further capabilities of the testing apparatus to diagnose anddemonstrate the source of problem in the electrical system of acustomers car. For this purpose, test meter 17 is not necessary, but theremainder of the apparatus forms a convenient unit for transporting thebooster battery 18 and the polarity protector 13 together with theindicators 31, 32 and 33 and the necessary connector cables, which serveto apply booster power to automobile 12 and to protect, as outlinedabove, against improper connection of clips 22 to the electrical system16.

For emergency roadside service to stalled automobiles and for othergeneral convenience in transporting the apparatus, the operator may, ifnecessary, demount the upper portion of handle 36 carrying housing 28and cables 20, 21 and 24 at telescoping joint 46. This enables the userof the testing apparatus to carry the apparatus around in a space oflimited vertical clearance such as the trunk of an automobile and yetallow booster battery 18 to remain upright to protect against spillageof battery acid. The hooks 44 provided on handle 36 allow cables 20, 21and 24 to be conveniently and attractively wound up out of the way whennot in use.

Clips may be stored by clamping them to any convenient part of theframework of cart 19, such as brace members 43 or axle 37, even thoughthose parts may be of conductive material, as the clips 22 remaindeenergized until such time as remote control switch 26 is closedconcurrently with application of a source of negative potential to cable21. As explosive hydrogen gas may be present in the vicinity of afreshly charged battery, the lack of application of potential to clips22 yields an advantageous safety feature of preventing hazardoussparking should clips 22 short together or against a common conductor.

The provision of the remote control means 23 which allows the operatorto step back a safe distance before electrically engaging the boosterbattery with the automobile electrical system 16 has a further safetyadvantage should a defect in system 16 be such as to cause hazardoussparking upon application of one of clips 22 to electrical system 16.The remote control means 23 also allows the operator to make the testsoutlined above from a convenient position, such as alongside thecustomer if he is demonstrating the test to a customer, or near thestarter switch of the automobile if he is testing the automobile byhimself. The booster battery will not be shorted out by carelessoperation of remote control means 23, as the booster battery is kept outof connection by polarity protector 13 until proper polarity is sensed.

From the foregoing, it will be seen that the present invention providesa novel and useful testing and booster power supply unit effective tomeasure the voltage present in the automobile electrical system underselected conditions of no load and heavy load and with a choice ofsources of power supply, such as the customer's battery or a boosterbattery. The unit protects the electrical system of the automobile fromthe imposition of incorrect polarity direct current and gives graphicindication of correct and incorrect hookup and of whether or not thebooster battery power source is being used. For both safety and ease ofdemonstration, the unit has been provided with a remote control meansand the connecting cables connecting to the customers automobileelectrical system as kept deenergized until correct polarity is sensedand the remote control means is operated. The unit provided may also beseen to be adaptable both for the starting of stalled automobilesthrough application of booster power thereto and for diagnosing thesource of electrical faults in the automobile electrical system.

I claim: 1. A method of evaluating performance of a specific battery ina specific automobile electrical system and ascertaining the electricalcondition thereof, comprising the steps of connecting a voltmeter acrossthe automobile s battery terminals while the latter are connected to theautomobile electrical system to measure voltage thereacross,

operating the automobile starter to crank the engine while preventingstarting of the engine to measure voltage thereacross under startingload,

connecting a fully charged high ampere-hour booster battery to theautomobile electrical system in parallel with the automobile 's battery,and

operating the automobile starter to crank the engine while preventingstarting of the engine to measure voltage across the terminals of theautomobiles battery for comparison of voltage in the automobileelectrical system under cranking load with and without said boosterbattery,

whereby if said electrical system is in a first condition wherein thevoltage is below a standard value with only the automobiles batteryconnected to the automobile electrical system while under cranking loadand is above said standard value when the booster battery is connectedto the automobile electrical system in parallel with the automobilesbattery while under cranking load the automobiles battery is at fault,and whereby if said electrical system is in a second condition whereinthe voltage is below said standard value when the booster battery isconnected to the automobile electrical system in parallel with theautomobiles battery while under cranking load the automobiles startersystem is at fault.

2. A method as described in claim 1, and wherein in the event saidelectrical system is in said first condition said method comprises theadditional steps of connecting a voltmeter across the automobilesbattery terminals while the latter are connected to the automobileelectrical system to measure voltage thereacross under no cranking loadconditions with the engine stopped, starting the engine of theautomobile and measuring the voltage across said terminals with theengine running, whereby if said electrical system is in a thirdcondition wherein the measured voltage under no cranking load conditionswith the engine stopped is below a first standard value the automobilesbattery is discharged, and whereby if said electrical system is in afourth condition wherein the measured voltage with the engine running isbelow a first standard value the generator is at fault and if saidelectrical system is in a fifth condition wherein the measured voltagewith the engine running is above a second higher value the voltageregulator is at fault.

3. A method as described in claim 1, and wherein in the event saidelectrical system is in said second condition said method comprises theadditional steps of connecting a voltmeter across the automobilesbattery terminals while the latter are connected to the automobileelectrical system to measure voltage thereacross with said boosterbattery connected in parallel and the engine stopped and the starter notcranking, whereby if said electrical system is in a sixth conditionwherein the measured voltage is below a standard value a short circuitis indicated in the electrical system outside the ignition and starterportions of the system.

4. A method as described in claim 1, and wherein in the event saidelectrical system is in said second condition said method comprises theadditional steps of connecting a voltmeter across the automobilesbattery terminals while the latter are connected to the automobileelectrical system to measure voltage thereacross with said boosterbattery connected in parallel and the engine not running and the startercranking, whereby if said electrical system is in a seventh conditionwherein the measured voltage is below a standard value a fault in thestarter system is confirmed, and whereby if said electrical system is inan eighth condition wherein the measured voltage is above said lastnamed standard value a fault in the automobiles battery is confirmed.

5. A method as described in claim 2, and wherein in the event saidelectrical system is in said fourth condition and not in said eighthcondition said method comprises the additional steps of measuring thevoltage across the booster battery terminals while the latter areconnected to the automobile electric system to measure voltagethereacross with the engine running and the automobile batterydisconnected from the automobile electrical system, whereby if themeasured voltage is below a standard value the generator is at fault andif the measured voltage is above a standard value the automobilesbattery is discharged.

1. A method of evaluating performance of a specific battery in aspecific automobile electrical system and ascertaining the electricalcondition thereof, comprising the steps of connecting a voltmeter acrossthe automobile''s battery terminals while the latter are connected tothe automobile electrical system to measure voltage thereacross,operating the automobile starter to crank the engine while preventingstarting of the engine to measure voltage thereacross under startingload, connecting a fully charged high ampere-hour booster battery to theautomobile electrical system in parallel with the automobile''s battery,and operating the automobile starter to crank the engine whilepreventing starting of the engine to measure voltage across theterminals of the automobile''s battery for comparison of voltage in theautomobile electrical system under cranking load with and without saidbooster battery, whereby if said electrical system is in a firstcondition wherein the voltage is below a standard value with only theautomobile''s battery connected to the automobile electrical systemwhile under cranking load and is above said standard value when thebooster battery is connected to the automobile electrical system inparallel with the automobile''s battery while under cranking load theautomobile''s battery is at fault, and whereby if said electrical systemis in a second condition wherein the voltage is below said standardvalue when the booster battery is connected to the automobile electricalsystem in parallel with the automobile''s battery while under crankingload the automobile''s starter system is at fault.
 2. A method asdescribed in claim 1, and wherein in the event said electrical system isin said first condition said method comprises the additional steps ofconnecting a voltmeter across the automobile''s battery terminals whilethe latter are connected to the aUtomobile electrical system to measurevoltage thereacross under no cranking load conditions with the enginestopped, starting the engine of the automobile and measuring the voltageacross said terminals with the engine running, whereby if saidelectrical system is in a third condition wherein the measured voltageunder no cranking load conditions with the engine stopped is below afirst standard value the automobile''s battery is discharged, andwhereby if said electrical system is in a fourth condition wherein themeasured voltage with the engine running is below a first standard valuethe generator is at fault and if said electrical system is in a fifthcondition wherein the measured voltage with the engine running is abovea second higher value the voltage regulator is at fault.
 3. A method asdescribed in claim 1, and wherein in the event said electrical system isin said second condition said method comprises the additional steps ofconnecting a voltmeter across the automobile''s battery terminals whilethe latter are connected to the automobile electrical system to measurevoltage thereacross with said booster battery connected in parallel andthe engine stopped and the starter not cranking, whereby if saidelectrical system is in a sixth condition wherein the measured voltageis below a standard value a short circuit is indicated in the electricalsystem outside the ignition and starter portions of the system.
 4. Amethod as described in claim 1, and wherein in the event said electricalsystem is in said second condition said method comprises the additionalsteps of connecting a voltmeter across the automobile''s batteryterminals while the latter are connected to the automobile electricalsystem to measure voltage thereacross with said booster batteryconnected in parallel and the engine not running and the startercranking, whereby if said electrical system is in a seventh conditionwherein the measured voltage is below a standard value a fault in thestarter system is confirmed, and whereby if said electrical system is inan eighth condition wherein the measured voltage is above said lastnamed standard value a fault in the automobile''s battery is confirmed.5. A method as described in claim 2, and wherein in the event saidelectrical system is in said fourth condition and not in said eighthcondition said method comprises the additional steps of measuring thevoltage across the booster battery terminals while the latter areconnected to the automobile electric system to measure voltagethereacross with the engine running and the automobile batterydisconnected from the automobile electrical system, whereby if themeasured voltage is below a standard value the generator is at fault andif the measured voltage is above a standard value the automobile''sbattery is discharged.